Here in India too the problem is the identical. The iBooks store only let's you purchase (without paying anything) and download really ancient publications which are free of any copyrights. Nothing that is more contemporary.
The same is the problem when you try to purchase music on the iTunes music store. I first thout it ws something to do with some financial regulations imposed by the Indian Government; however, I reasised soon thwt tht was not the case at all. It is something wierd with the stores.
The most ironical thing is that you can purchase Apps on the AppStore and pay for them using your Credit Card with an address in India.
I know that if the address is faked, the paid content on both iTunes and iBooks open up. (I have seen someone do this.)
Here is what I could infer: You need to have an address in the UK, the US, or some other locations that apple has qualified to be countries from where you can purchase paid content to shop for music and books on iTunes and iBooks. Although younger not permitted to pay and download books nd music, you may pay and download software without any restrictions. This is really weird.
Additionally, please note - People I know who use the Kindle (device) can pay and download just about any content without any restrictions whatsoever.
Ajit